vaughan



March 20, 1928.

C. VAUGHAN MOLD AND METHOD OF CASTING Filed Feb. 7, 1 923 2 Sheets-Sheet1 I nus-11 707?. W s I 6mm B)- Z t Vow- March 20, 1928. 1,663,286 IC.VAUGHAN MOLD AND METHOD OF CASTING Filed Feb. 7, 1923 2 Sheets-Sheet.2

Patented Mar. 20. 1928.

UNITED I srn'rss PATENT OFFICE.

CONRAD \FAUGHAN, CF CLEVELAND, OHIO, ASSIGNOR TO THE PERMOLD COMPANY, OFCLEVELAND, 01110, A CORPORATION OF OHIO.

MOLD AND METHOD OF CASTING.

Application fil d February This invention re '1 molds and a method. offorming castings, the i. ivention being particularly useful in fornr lugcastings of aluminum alloys alloys having relatively highcrystallization shrinkage and relatively low lfreezing point.

An obj ;ct of the lure on to retard he conduction of heat from that partof the l torn ing the srue cayity so the the using of the metal thespruc cavity is carded and smaller amount of metal sorue is required forproperly fee-1 1 1 p e casting as it solidifi s in the znoro. c;

hes to permanent metal roperly fed because freezi of the mo 7 isretarded no l r the metal has solidified in the mold ity.

to provide a mold in may be made in due to the use or ation temperaturel r will be a smmler excess of metal in the spine cavity.

A further object of the invention to i .o a mold in which the time forsolidi- 1. L' o 3 a relative sins: V c v. 1 o snrjuo and in Arno.- weo.4 i Y zxve, J0 Lkllob I ape or the casting I the: ob ects in.iiOWlIlfl oescrmti ii Reference should be 1 I forming i. and

the upper and lower mo tZo-ns, shown in Figs. 2 a a) a plane at rightangles to that shown in Fig. 1.

Figs. -1- and 5 are a side elevation and bet- 7, 1923. Serial No.617,439.

tom plan view, respectively, of a casting formed in the mold.

Fig. 6 is a plan view of the mold after the metal has solidifiedtherein.

Fig. '7 is a section on line 7-7, Fig. 1.

Referring to the accompanying drawings, the lower section or base 1 ofthe mold is in the form of a stand with side legs 2 and a 0 top in whichthe mold cavity 4 is formed. The mold cavity 4 has an open cylindricalbottom portion 5 in which fits a plunger 6 which carries an upwardlyprojecting core 7 t its upper end. The plunger (3 has a down- '"zu'dlyextending stem 8 which fits in an opening in a cross bar 9 connectingthe legs 2 ljacent their lower ends. A lever 10 is pivoted upon crosspin 11 extending between the legs :2 adjacent one side thereof 7 andextends through an opening 12 in the stem 8. A cross pin 13 extendsthrough the plunger 6 and serves to positively limit the upward movementof the plunger. The upper and lower edges of the opening 12 are 7rounded so that the lever 10 does not bind therein when swung about itspivot. When the mold core is in operative position for casting, the pin18 is in engagement with the bottom of the mold as shown in Fig. 1 theplunger 6 and core 7 being movable downwardly from this position to thatshown in l? ig. 2 "to free the core from the castin The upper moldsection 14 has handles 15 by means of which it can be readily lifted oili. bottom section '1. and has a lower flange 16 adapted to lit withinthe upper portion of lhe mold cavity 4.

lhe mold section 14 has a central bore 17 ri h apers slightly toward thebottom to to removal of the casting and spruc, ell understood. The moldsection 14 also provided with an annular air chamoer 22 preferably withoutside openings therein. An easy method of providing such a chamber isto form a tubular liner 18 with thin intermediate portion 21 spaced fromthe wall of the bore 17, and thick up or and lower edge portions 19 and20 fitting tightly in the bore 17.

hen the mold is assembled as shown in Fig. 1, the inner bore of theliner 18 forms the mold gate and sprue recess,the annular passagebetween the core 7 and the lower portion of the liner 18 forming thegate and the remainder of the bore the sprue recess. To facilitate theremoval of castings from the mold both the core 7 and the inner bore ofthe liner 18 forming the sprue recess are tapered slightly toward thetop so that the core can be pulled downwardly out of the casting and thesprue can be readily freed from the mold.

Surrounding the mold cavity and prefer ably located near the heavysection of the casting and remote from the gate a fluid passage 31 tocarry any suitable fluid, pref erably a liquid such as water or oil,therethrough to cool the mold and consequently to cool the molten metalremote from the gate or in the heavy sections of the casting.

This passage may follow the shape oi. the mold cavity and be formed inany suitable manner as by cores when casting the mold, or it may beformed of a rectangular shape, as shown in Fig. 7, by boring into themold after the mold has been cast.

In operation, the mold sections will be assembled as shown in Fig. 1 andmolten metal will be poured in at the top until both the cavity t in thelower section and the s rue cavity are filled. As the solidification ofthe metal in the mold cavity takes place, additional metal is suppliedfrom the sprue cavity. It has heretofore been necessary to provide arather large sprue recess to maintain a sufi'icient reserve supply ofmolten metal and to have a sprue recess of a sufficient diameter thatthe center of the sprue would remain fluid long enough to supply thenecessary metal to the mold cavity. The present invention, however,provides a construction for the sprue cavity which retards the loss ofthe heat in the sprue and delays freezing until after the casting hashardened in the mold. cavity and thus permits the relatively smallamount of metal in the sprue cavity to properly feed the solidifyingcasting. The annular air chamber 22 surrounding the sprue cavity retardsthe loss of heat for it decreases the volume of metal f r directlyconducting the heat away from the sprue cavity so that the metal in thesprue may be nuiintained molten for a longer period oftime and arelatively larger percentage of the sprue metal is available for feedingthe casting.

That the metal for feeding the casting is drawn from sides of the sprueas well as down through the center, as is usual, is shown by the shapeof solidified. sprue metal in Figs. 2 and 4;, wherein the side 28 isconcaved all the way around. In Fig. 4: the casting 24; is shown in fulllines and the sprue 25 in dotted lines, the casting 2% after the sprueis removed having a central aperture 26.

If it is desired to hasten the cooling and solidification of the metalin the sprue after neeaaee the casting is solidified, any suitablefluid, such as compressed air, can be circulated around the passage 22through the openings 30, thus greatly reducing the time of waiting afterthe casting is solidified and until the sprue is sufiiciently solidifiedto remove the core 7.

It will thus be seen that by varying the size of the annular passagesurrounding the sprue cavity, the length of time that the sprue metalmay be held in molten condition can be varied. Also by varying thetemperature or quantity of iluid supplied to the body of the mold, thecooling time of the casting itself may be varied. Also by thecirculation of air through. the annular passage 22 surrounding the spruecavity, the time of solidification of the .sprue after the casting issolidified may be decreased so that the core may be removed morequickly. By providing these variables it is possible to design molds formany shapes of casting which will greatly increase the production yieldper mold per day for provision can he made for removing heat as fast asdesirable from the heavier sections of the casting or sections moreremote from the gate. And the sprue may be kept molten a sullicientlength of time to properly feed the casting on solidification and maythen be rapidly cooled to facilitate production. Or if desired, theannular passage may be designed to balance the time for keeping themetal molten in the sprue as long as necessary and permitting it to cooland solidify immediately thereafter without the use of a circulatingfluid.

Furthermore, it will be noted that by providing means for retarding thecooling of the metal in the sprue a relatively less amount of metal isnecessary for properly feeding the casting for a relatively largerpercent of the metal in the sprue is available for this purpose. It willthus be seen that castings may be made according to this invention in.which the is of relatively small cross'sectional area or in which allparts of the gate are relatively narrow, so that the tendency to formpipes is prevented and the character of the metal in the casting isimproved.

l urthermore, it is to be understood that the particular forms of:apparatus shown and described, and the particular procedure set forth,are presented for purposes of explanation and illustration and thatvarious modifications of said apparatus and procedure can be madewithout departing from my invention as defined in the appended claims.

lVhat I claim is:

1. The method of forming castings of metal of a relatively highcrystallization shrinkage and a relatively low freezing point whichconsists in introducing molten metal of such characteristics into apermanent mold having a mold cavity and sprue cavity, cooling the moldadjacent the more remote sections 01" the casting and then cooling thatportion of the mold surrounding the sprue cavity.

2. The method of forming castings having thin and thick sections ofmetal of relatively high crystallization shrinkage and relative- 1y 10Wfreezing point, which consists in introducing molten metal of suchcharacteristies into a permanent mold having a mold cavity and spruecavity, retarding the escape of heat from the sprue cavity andfacilitating the escape of heat from the thicker sections of thecasting, and then accelerating the cooling of the metal in the spruecavity after the metal in the mold cavity has solidified.

3. The method of forming castings of relatively high crystallizationshrinkage and relatively low freezing point, which consists inintroducing molten metal of such characteristics into a permanent moldhaving a mold cavity and sprue cavity, retarding the escape of heat fromthe sprue cavity until after the mold cavity is filled and the metaltherein has substantially solidified.

In testimony whereof, I hereunto aflix my signature.

CONRAD VAUGHAN.

